There are many and well-known solvent extraction processes. Typically, a sample is combined with a solvent in a container and the is contents of the container mixed by mechanical agitation, such as stirring or shaking. After the solvent and sample are thoroughly mixed, the mixture is allowed to stand over time such that the material to be removed from the sample is solubilized in the solvent and the solvent with the solubilized material separates from the sample. The separation is effected conventionally by gravity, that the density of the solvent with solubilized sample is different from the density of the sample. Typically, the density of the solvent with solubilized material is less than the density of the sample such that the solvent with the solubilized material rises to the surface of the container. The solvent with the solubilized material is drawn off from the vessel and additional clean solvent is combined with the remaining sample and the process is repeated until the desired concentrations are reached. It will be appreciated that processes such as described are used to either purify the sample or to recover the material from the sample, or both.
In the foregoing-described process, it will be further appreciated that the steps necessary to perform the process involve use of a substantial number of various component parts, as well as significant handling of those parts. This causes a variety of problems. For example, the repeated processing of the sample places it in contact with a large number of parts such as mixers, stirrers and various containers. There is a significant potential for contaminating the sample and/or the solvent with foreign substances from those parts. Further, there is the potential danger of splashing the sample or solvent, or both, which could be hazardous to the individuals performing the extraction process, particularly where the solvents are toxic. Still further, multiple measuring and liquid transfers occur in such systems. These are not only labor-intensive but prone to error and increase the likelihood of loss.